B-lactam mediated SOS response and expression of resistance in clinical MRSA

Summary

Principal Investigator: Adriana E Rosato
Abstract: DESCRIPTION (provided by applicant): One of the most contemporary challenges to the treatment of hospital-acquired infections worldwide is the appearance and global spread of staphylococci resistant to all ?-lactam antibiotics (known as methicillinresistant Staphylococcus aureus;MRSA). More recently, MRSA has also become established outside of the hospital, appearing in community populations without healthcare association or identifiable risk factors for infection. In either case, resistance to ?-lactam antibiotics is due to the acquisition of a gene (mecA) that encodes a ?-lactam insensitive target enzyme, penicillin-binding protein (PBP)2a. This enzyme affords the bacterium the ability to cross-link cell wall and grow while the cell's usual cross-linking enzymes are bound and inactivated by ?-lactam antibiotics. Several studies have shown that the morbidity and mortality in infections due to MRSA are considerably higher than in MSSA (methicillin susceptible Staphylococcus aureus) infections, mainly because of an inadequate initial antimicrobial therapy. As a consequence, accurate detection of methicillin resistance in S. aureus is not only clinically important but essential for hospital infection control programs. ?-lactam antibiotics are agents of choice to treat (MSSA) because of their bactericidal activity. The main characteristic of MRSA strains is their heterogeneous expression of ?-lactam resistance. We have examined a number of clinical MRSA strains that are misinterpreted as MSSA due to their extreme heterogeneity. These isolates were referred to our laboratory from the Centers for Diseases Control and Prevention (CDC, Atlanta, GA) as clinically relevant since exposure of such isolates to ?-lactams can result in high-level resistance (HoR). Indeed, we have determined in a representative strain SA13011, that selection from heterotypic ((HeR) to homotypic resistant (HoR) phenotype occurred after exposure to sub-inhibitory concentrations of ?-lactam antibiotics. This selection involved, in addition to increasing expression of MecA, the triggering of ?-lactam-mediated SOS response and increased mutation rate. Therefore, the central hypothesis of this proposal is that upon exposure to ?-lactams, SA13011 is selected from heterotypic (HeR) to homotypic resistant phenotype (HoR) by a ?-lactam-induced SOS response that leads to an agr-genetically controlled increased mutation rate that helps to maintain, among others, the cell wall integrity. SA# 1.To define the role of ?-lactam induced SOS response on the development of high level resistance to oxacillin in the clinical methicillin- resistant isolate SA13011. SA# 2. To identify the mechanisms involved in ?-lactam-induced SOS response induction and cell wall integrity during oxacillin-mediated HeR-HoR selection SA #3. To investigate the regulatory role of agr in ?-lactam-induced SOS- response and mutation rate. PUBLIC HEALTH RELEVANCE: Clinical Methicillin-Resistant S.aureus (MRSA) isolates expressing low levels of resistance and being misinterpreted as oxacillin-susceptible are a growing concern. These strains spread unnoticed in the hospital environment in both patients and staff. Oxacillin susceptible low level mecA mediated resistance MRSA strains are very heterogeneous (HeR) in expression and clinically relevant since exposure of such isolates to ?-lactams can result in high-level resistance. The central hypothesis of this proposal is that upon exposure to ?-lactams, MRSA (SA13011) is selected from a heterotypic (HeR) to a homotypic resistant phenotype (HoR) by a ?-lactam-induced SOS response that leads to an agr-genetically controlled increased mutation rate that helps to maintain, among others, the cell wall integrity.
Funding Period: 2010-04-01 - 2015-03-31
more information: NIH RePORT

Top Publications

  1. pmc Fate of mutation rate depends on agr locus expression during oxacillin-mediated heterogeneous-homogeneous selection in methicillin-resistant Staphylococcus aureus clinical strains
    Konrad B Plata
    Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, Houston, Texas 77030, USA
    Antimicrob Agents Chemother 55:3176-86. 2011
  2. pmc β-Lactams increase the antibacterial activity of daptomycin against clinical methicillin-resistant Staphylococcus aureus strains and prevent selection of daptomycin-resistant derivatives
    Shrenik Mehta
    Department of Pathology and Genomic Medicine, The Methodist Hospital Research Institute, Houston, TX, USA
    Antimicrob Agents Chemother 56:6192-200. 2012
  3. pmc Targeting of PBP1 by β-lactams determines recA/SOS response activation in heterogeneous MRSA clinical strains
    Konrad B Plata
    Department of Pathology and Genomic Medicine, The Methodist Hospital, Houston, Texas, United States of America
    PLoS ONE 8:e61083. 2013
  4. pmc Exposure of clinical MRSA heterogeneous strains to β-lactams redirects metabolism to optimize energy production through the TCA cycle
    Mignon A Keaton
    Metabolon, Inc, Durham, North Carolina, United States of America
    PLoS ONE 8:e71025. 2013
  5. pmc Identification of point mutations in clinical Staphylococcus aureus strains that produce small-colony variants auxotrophic for menadione
    Melissa A Dean
    Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
    Infect Immun 82:1600-5. 2014
  6. pmc Staphylococcal phenotypes induced by naturally occurring and synthetic membrane-interactive polyphenolic β-lactam resistance modifiers
    Lucía Palacios
    School of Pharmacy, University College London, London, United Kingdom
    PLoS ONE 9:e93830. 2014

Detail Information

Publications6

  1. pmc Fate of mutation rate depends on agr locus expression during oxacillin-mediated heterogeneous-homogeneous selection in methicillin-resistant Staphylococcus aureus clinical strains
    Konrad B Plata
    Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, Houston, Texas 77030, USA
    Antimicrob Agents Chemother 55:3176-86. 2011
    ....
  2. pmc β-Lactams increase the antibacterial activity of daptomycin against clinical methicillin-resistant Staphylococcus aureus strains and prevent selection of daptomycin-resistant derivatives
    Shrenik Mehta
    Department of Pathology and Genomic Medicine, The Methodist Hospital Research Institute, Houston, TX, USA
    Antimicrob Agents Chemother 56:6192-200. 2012
    ....
  3. pmc Targeting of PBP1 by β-lactams determines recA/SOS response activation in heterogeneous MRSA clinical strains
    Konrad B Plata
    Department of Pathology and Genomic Medicine, The Methodist Hospital, Houston, Texas, United States of America
    PLoS ONE 8:e61083. 2013
    ....
  4. pmc Exposure of clinical MRSA heterogeneous strains to β-lactams redirects metabolism to optimize energy production through the TCA cycle
    Mignon A Keaton
    Metabolon, Inc, Durham, North Carolina, United States of America
    PLoS ONE 8:e71025. 2013
    ....
  5. pmc Identification of point mutations in clinical Staphylococcus aureus strains that produce small-colony variants auxotrophic for menadione
    Melissa A Dean
    Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA
    Infect Immun 82:1600-5. 2014
    ..Analysis of genetic revertants and complementation with wild-type alleles confirmed that these mutations caused the SCV phenotype and decreased virulence for mice. ..
  6. pmc Staphylococcal phenotypes induced by naturally occurring and synthetic membrane-interactive polyphenolic β-lactam resistance modifiers
    Lucía Palacios
    School of Pharmacy, University College London, London, United Kingdom
    PLoS ONE 9:e93830. 2014
    ..The ability to enhance these properties by chemical modification of ECg raises the possibility that more potent analogs could be developed for clinical evaluation. ..

Research Grants30

  1. The Shelf Live Evaluation of Investigational Dosage Forms
    Jonathan White; Fiscal Year: 2013
    ..This contract is essential for continued assurance of the quality of drugs undergoing clinical investigation for different types of cancer by Cancer Therapeutics Evaluation Program. ..
  2. Role of Staphylococcus aureus alpha-hemolysin in disease
    Juliane Bubeck Wardenburg; Fiscal Year: 2013
    ..These studies are expected to shed light on elements of host susceptibility to S. aureus disease, and contribute more broadly to our understanding of bacterial pore forming cytotoxins. ..
  3. Mechanisms of S. aureus transmission and persistence.
    Anne Catrin Uhlemann; Fiscal Year: 2013
    ..We have limited understanding of how these bacteria spread and why they persist. This research will help to find out how some of these strains survive and enable us to design interventions to limit their spread. ..
  4. Inhibitors of S. aureus bNOS for adjunctive therapy
    Donald T Moir; Fiscal Year: 2013
    ..These new drugs will prolong the duration of effective concentrations of existing antibiotics, thus reducing selection for resistance and improving therapy. ..
  5. Impact of Antibiotics and PBP2a on the Immunopathology of MRSA pneumonia
    David M Underhill; Fiscal Year: 2013
    ..In the second aim, we will move to in vivo mouse pneumonia models to determine the effects of antibiotics and PBP2A expression by MRSA on immunopathology. ..
  6. Impact of the Nasal Microbiome on S. aureus Colonization and Infection
    Mary Bessesen; Fiscal Year: 2013
    ..abstract_text> ..
  7. TH17 Autoimmunity to Type V Collagen in Heart and Lung Transplant
    David S Wilkes; Fiscal Year: 2013
    ..abstract_text> ..
  8. Harvard-wide Program on Antibiotic Resistance
    Suzanne Walker; Fiscal Year: 2013
    ..One compound already has been validated, and the goal of this program is to deliver 10 more along with advancing the attendant science ..
  9. A New Approach to Staphylococcus aureus Vaccine Development - Resubmission 01
    Brad J Spellberg; Fiscal Year: 2013
    ..It is expected that our combination vaccine development protocol will offer new insight into strategies for protection against invasive disease and SSTIs. ..
  10. Caloric Restricted Rodent Colony
    RICK MORIN; Fiscal Year: 2013
    ..The purpose of this project is to develop, maintain and distribute a standing colony ofaged, calorically restricted rodents ofdefined strains for use by investigators in studies of aging. ..
  11. Reduction of Tunneled Dialysis Catheter Dysfunction Via Long Term Nitric Oxide Re
    Prabir Roy-Chaudhury; Fiscal Year: 2013
    ..This technology has been optioned by Biocrede Inc. via the Office of Tech Transfer at the University of Michigan. ..
  12. Identifying and validating new antibiotic targets in cell wall synthesis pathways
    Suzanne Walker; Fiscal Year: 2013
    ..coli will be broadly relevant to our understanding of cell wall polymer biogenesis in other microorganisms and should significantly impact and inform efforts to generate therapies against MRSA and Gram-negative ESKAPE pathogens. ..
  13. Cell wall synthesis enzymes and beta-lactam resistance in Enterococcus faecium
    Louis B Rice; Fiscal Year: 2013
    ..They will also enhance our understanding of cell wall synthesis mechanisms in Gram-positive cocci and reveal promising new targets for antibacterial therapy. ..
  14. Rocky Mountain Regional Center of Excellence or Biodefense and Emerging Infectiou
    John T Belisle; Fiscal Year: 2013
    ..abstract_text> ..
  15. Vaccine Assembly from Surface Proteins of Staphylococcus Aureus
    Olaf Schneewind; Fiscal Year: 2013
    ..abstract_text> ..
  16. STAPHYLOCOCCAL METHICILLIN RESISTANCE LOCUS
    GORDON LEE ARCHER; Fiscal Year: 2013
    ..In addition, it will investigate conditions that promote the loss of this gene that may suggest strategies for reducing the hospital prevalence of MRSA. ..
  17. IMpact of PRObiotics for reducing infections in VEterans: The IMPROVE Study
    Nasia Safdar; Fiscal Year: 2013
    ..If found to be efficacious, probiotics represent an easily implementable, safe, and well-tolerated intervention that is suitable for use in a field environment and requires no special conditions for it to be used. ..
  18. Protein-protein interaction essential for bacterial growth and virulence
    Mark A Saper; Fiscal Year: 2013
    ..Moreover, the mode of ac- tion of such an inhibitor would be complementary with, but different from, ?-lactams. ..
  19. Computationally optimized anti-staphylococcal biotherapeutics
    Karl E Griswold; Fiscal Year: 2013
    ..aureus infections. ..
  20. Apolipoprotein B and Control of S. aureus Quorum Sensing
    PAMELA RANEL HALL; Fiscal Year: 2013
    ..abstract_text> ..
  21. Obstetric Pharmacology Research Units Network Center at UTMB-Galveston
    Gary D Hankins; Fiscal Year: 2013
    ....
  22. Oklahoma Center for Respiratory and Infectious Diseases
    Lin Liu; Fiscal Year: 2013
    ..The completion of the goals of the present COBRE will have a major impact on research programs on respiratory infectious diseases in the State of Oklahoma. ..
  23. Pacific NorthWest Regional Center of Excellence (PNWRCE)
    Jay A Nelson; Fiscal Year: 2013
    ..pseudomallei host pathogen response during both the septicemic as well as the intracellular phases of the disease. ..
  24. Bacterial fermentation in skin microbiome as probiotics (Bfismp) against S. aureu
    Chun Ming Huang; Fiscal Year: 2013
    ..The impact of this proposal includes opening a novel skin-care industry of using Bfismp for treating skin infection and/or promoting skin health. ..
  25. Antibiotic resistant genes and resistant phenotypes in MRSA and VISA strains
    Alexander Tomasz; Fiscal Year: 2013
    ....
  26. Novel Mechanisms of Beta-lactam Resistance in Staph Aureus
    Henry F Chambers; Fiscal Year: 2013
    ..Recombinant GdpP also will be purified and analyzed by x-ray crystallography to identify its critical structural properties. Achieving these aims will increase knowledge of ?-lactam antibiotic effects and mechanisms of resistance. ..